JP2009204001A - Center lubricating oil feeding crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crankshaft capable of feeding engine oil to each crank journal and crank pin under stable pressure. <P>SOLUTION: A center lubricating oil feeding crankshaft 10 is provided with an oil introducing hole 14i bored on one end 10a side for introducing engine oil, and a feeding oil passage 14 for feeding engine oil introduced from the oil introducing hole 14i to journal distributing oil passages 17a to 17e and pin oil passages 18a to 18d formed in crank journals 12a to 12e and crank pins 11a to 11d respectively. Oil chambers 15a to 15e are formed in each crank journal 12a to 12e to store engine oil circulating on an oil feed passage 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crankshaft of an internal combustion engine, and more particularly, to an oil passage structure in a center oil supply type crankshaft that supplies oil from one end of the crankshaft and supplies oil to all crank journals and crankpins through a single oil passage. .

  In general, a crankshaft of an internal combustion engine such as an automobile has a configuration in which a plurality of crankpins and a plurality of crank journals are alternately arranged. Since the crank pin is in sliding contact with the bearing at the large end of the connecting rod, and the crank journal is in sliding contact with the bearing of the journal portion of the crank case, it is always necessary to supply engine oil to these sliding contact surfaces.

  As a method for supplying engine oil to the crankshaft, the following journal oil supply method is generally employed. That is, each crank journal is provided with an oil passage penetrating perpendicularly to its axis (hereinafter referred to as a journal distribution oil passage), and a sliding contact surface with the crank journal from an oil passage in an annular groove provided on the inner surface of the journal bearing; Engine oil is supplied to the journal distribution oil passage, and similarly, each crank pin is provided with an oil passage (hereinafter referred to as a pin distribution oil passage) penetrating perpendicularly to the axis thereof, and the crank journal shaft of the journal distribution oil passage. Drilling from the crank pin side an oil passage (hereinafter referred to as a supply oil passage) that connects the core portion and the crank pin shaft center portion of the adjacent pin distribution oil passage, and closing the end portion with a plug. Thus, the engine oil is supplied to the sliding contact surface of each crank pin with the connecting rod.

  On the other hand, this type of oil supply method requires a high pressure to pump engine oil to the journal shaft against the centrifugal force of the rotating crank journal. In addition, journal distribution oil passages 56a to 56e perpendicular to the axis of each crank journal 52a to 52e are provided, and similarly, pin distribution oil passages 55a to 55d orthogonal to the axis thereof are provided to the crank pins 51a to 51d. A so-called center oil supply system in which engine oil is supplied to all crank journals 52 and crank pins 51 through a single oil supply passage 54 from an oil introduction hole 54a formed on one end 50a side of the crankshaft 50. (This type is hereinafter referred to as a solid crankshaft). In the center oil supply method, compared to the journal oil supply method, the oil pressure when the engine oil is sent to the supply oil passage 54 can be kept low, so that the oil pump can be downsized.

As a center oil supply type crankshaft, in order to realize cooling of the sliding contact portion and reduction of the shaft weight, a hollow chamber is formed in each crank journal and a crankpin, and adjacent hollow chambers are connected by an oil passage. An assembly-type crankshaft has been proposed in which a molded body positioned with a spacer in the crankshaft direction and the radial direction is inserted into the hollow chamber (see Patent Document 1). In addition to reducing the amount of engine oil used by installing the molded body in the hollow chamber, this assembly type crankshaft not only reduces the amount of engine oil used, but also regulates the direction of the engine oil flow and cools the hollow chamber wall surface with sufficient flow rate I am trying.
JP-A-9-126219

  However, in the center oil supply method including Patent Document 1, the crankshaft is deformed by the centrifugal force of the crankshaft and the load received from the connecting rod, and the oil supply by the pin distribution oil passage of the crankpin is intermittent. As a result, there is a problem that pulsation occurs. In addition, since the supply oil passage is long and extends meandering along the axis of the crankshaft, a pressure drop is likely to occur in the engine oil.

  Further, in the crankshaft described in the above cited reference 1, since a hollow chamber is formed also in the crankpin to which the load of the piston or the connecting rod is directly applied, rigidity and vibration are compared with a crankshaft having a solid crankpin. , Disadvantageous in terms of noise. In this regard, in order to ensure the same degree of rigidity as that of a solid crankpin, for example, it is necessary to increase the diameter of the crankpin. However, this approach increases the frictional resistance around the crankshaft and the connecting rod in proportion to the increase in the number of rotations in a high-speed and high-power engine, and the large end of the connecting rod increases in size and the inertia weight increases. This is not desirable for reasons such as that. Furthermore, if a minute amount of air in the engine oil accumulates in the hollow chamber of the crankpin, the accumulated air may flow out at a time due to a change in the operating state or the like, thereby interrupting the supply of engine oil.

  The present invention has been made in view of such a background, and an object thereof is to provide a crankshaft capable of supplying engine oil to each crank journal and crankpin with a stable pressure.

  In order to solve the above-described problems, the present invention has an oil introduction hole into which engine oil is introduced near one end thereof, and the engine oil introduced from the oil introduction hole is supplied to each crank journal and each crank pin. In a center oil supply type crankshaft provided with a supply oil passage for supplying to the formed distribution oil passage, at least one oil chamber for storing engine oil flowing through the supply oil passage is formed only in the crank journal. Shall.

  In the crankshaft having the above-described configuration, the oil chamber may be formed in a substantially cylindrical shape having the crankshaft as its center. In this case, the oil chamber has small diameter portions at both ends, and the supply oil It is good to comprise so that a path may be opened to the said small diameter part. The sum of the volumes of the oil chambers may be at least twice the sum of the volumes of the distribution oil passages.

  According to the present invention, even if pulsation occurs in the engine oil due to the deformation of the crankshaft caused by the load received from the connecting rod, the centrifugal force of the crankshaft, etc., the pulsation is reduced by the oil chamber, and stable to each crank journal and crankpin. The engine oil can be supplied at a reduced pressure. Further, since the oil chamber is formed only in the crank journal, fine air is not collected in the oil chamber of the crankpin, and the rigidity of the crankpin is not lowered.

  In addition, by making the oil chamber substantially cylindrical with the crankshaft as its axis, engine oil flows in the oil chamber without being affected by centrifugal force, so pressure loss is reduced. Further, the oil chamber has small diameter portions at both ends thereof, and the supply oil passage opens to the small diameter portion, so that engine oil flows into the oil chamber from the supply oil passage and into the supply oil passage from the oil chamber. At this time, the cross-sectional area of the oil passage gradually decreases or gradually increases, so that the oil pressure can be suppressed and the engine oil can be distributed well. Further, by making the sum of the volumes of the engine oil oil chambers equal to or more than twice the sum of the volumes of the distribution oil passages, a good pulsation reducing effect can be exhibited.

  Hereinafter, an embodiment in which the present invention is applied to an inline 4-cylinder gasoline engine (hereinafter simply referred to as an engine) E will be described in detail with reference to the drawings.

<< Configuration of Embodiment >>
FIG. 1 is a cross-sectional view of a main part of an engine E provided with a crankshaft 10 according to the embodiment. As shown in the drawing, the engine E is formed integrally with the cylinder head 1 that forms the first to fourth cylinders 2a, 2b, 2c, and 2d arranged in series in the crankshaft direction and the lower part of the cylinder head 1. The crankcase 3, the bearing block 5 fastened to the lower part of the crankcase 3, the crankshaft 10 rotatably supported by the crankcase 3 and the bearing block 5, and disposed below the bearing block 5, store engine oil. An oil pan 7 and the like are provided.

  The crankshaft 10 includes first to fourth crank pins 11a, 11b, 11c, and 11d, first to fifth crank journals 12a, 12b, 12c, 12d, and 12e, a counterweight, and these crank journals 12a. To 12e and the crank pins 11a to 11d are provided with four pairs of crank arms 13a, 13b, 13c and 13d which are connected while being alternately arranged. Each crank journal 12 includes first to fifth journal portions 4a, 4b, 4c, 4d, 4e formed on the crankcase 3 and first to fifth journal portions 6a, 6b formed on the bearing block 5. 6c, 6d, and 6e are pivotally supported by way of a half bearing metal 8, respectively. In the four crank pins 11a to 11d, the first and fourth crank pins 11a and 11d are the same crank angle, and the second and third crank pins 11b and 11c are 180 degrees different from the first and fourth crank pins 11a and 11d. The crank angle is set. Each crankpin 11 has large end portions 31a, 31b, 31c, 31d of first to fourth connecting rods connected to four pistons (not shown) that slide in the cylinders 2, and are also divided into half bearings. It is pivotally attached via a metal 9.

  A cam chain sprocket 32 around which a cam chain (not shown) that drives a cam shaft disposed above the cylinder head 1 is wound is fitted on the crankshaft 10 outside the engine of the first crank journal 12a. Further, an inner rotor 36 of a thin trochoid engine oil pump 33 (hereinafter simply referred to as an oil pump) is fitted on the outer side of the pump cover inner 34 with a pump cover inner 34 interposed therebetween. Along with this, a pump chamber 38 of the oil pump 33 is defined, and an inner rotor 36 is accommodated therein. An outer rotor 37 surrounding the inner rotor 36 is rotatably disposed in the pump chamber 38. When the crankshaft 10 drives the inner rotor 36 to rotate, the outer rotor 37 rotates with the inner rotor 36, and is generated between the two rotors. Engine oil is sucked and discharged by the change of the space volume. Further, a crank pulley 39 for driving an engine auxiliary machine such as an AC generator is fitted on one end portion 10a side of the crankshaft 10.

  An oil strainer 30 to which an oil supply pipe 31 communicating with the suction side of the pump chamber 38 of the oil pump 33 is connected is installed near the bottom surface inside the oil pan 7. The oil strainer 30 removes dust, rust, etc. contained in the engine oil when supplying oil to the engine E.

  The crankshaft 10 has an oil introduction hole 14i that opens to the discharge side of the pump chamber 38 of the oil pump 33 in the vicinity of one end portion 10a thereof, and supplies one engine oil to each crank journal 12 and each crankpin 11. This is a so-called center oil supply type provided with a supply oil passage 14. The supply oil passage 14 is composed of a part of a plurality of perforations drilled linearly from the outer surface of the crank arm 13 by straight drilling, that is, a combination of portions extending from the perforation intersection to the oil chamber 15. It extends as a single oil passage that passes through all the crank journals 12a to 12e and the crank pins 11a to 11d while being bent. The remaining perforated portion from the intersection to the outer surface of the crank arm 13 is closed with a steel ball plug 16 inserted from the opening on the crank arm 13 side, so that the engine oil can flow to the portion. It is blocked. In addition, oil chambers 15a, 15b, 15c, 15d, and 15e are formed inside the crank journals 12a to 12e, and a supply oil passage 14 communicates the oil chambers 15a to 15e.

  The crankshaft 10 is joined to each other at an intermediate portion of each of the crank journals 12a to 12e, and is disposed at both ends of the first to fourth throw pieces 21, 22, 23, and 24 that constitute one throw, and the crankcase 3 It is formed from two extension pieces 25 and 26 extending from. Each of the pieces 21 to 26 is a forged product, and is formed with a supply oil passage 14 after molding, and after being removed of burrs and shavings, they are friction bonded to each other. A concave portion is formed in the joining surface of each piece 21 to 26 during molding, and the oil chamber 15 is formed in the crank journal 12 by joining both pieces. The friction joint is deformed at the time of joining and extends radially inward and outward, but the part extending outward is ground by a cylindrical grinder after joining, and the outer peripheral surface of the crank journal 12 has a true cylindrical shape.

  Here, it is desirable that the joint portions of the pieces 21 to 26 are positioned at 1/4 to 3/4 of the length of the crank journals 12a to 12e in the crankshaft direction. This is because if the joint portion is formed at the end of the journal, the thickness of the crank journal 12 (thickness around the oil chamber 15) is increased because the crankshaft 10 cannot withstand the stress when rotating. This is because by taking such measures as described above, the diameter of the crank journal 12 or the oil chamber volume must be reduced.

  Next, the oil chamber and the oil passage will be described with reference to FIGS. 1 and 2. FIG. 2 is an enlarged cross-sectional view of the crankshaft 10 showing the third and fourth slow pieces 23 and 24. In FIG. 1, some symbols are omitted in order to avoid complication of the figure, but the suffixes a to e attached to the numbers of the respective symbols are the oil chambers 15 a to 15 e and Since it is continuous corresponding to the crankpins 11a to 11d, refer to FIG. 1 for the arrangement of symbols not shown in FIG.

  The oil chambers 15a to 15e have a substantially cylindrical shape with the axis A of the crankshaft 10 as its axis, and include small diameter portions 19a to 19e at both ends and large diameter portions 20a to 20e at intermediate portions, respectively. Yes. And the cyclic | annular joining deformation | transformation part 20'a-20'e deform | transformed at the time of joining protrudes to radial inside in large diameter part 20a-20e. The oil passage constituting portions 14a to 14d in the respective slow pieces 21 to 24 constituting the supply oil passage 14 are bent at the perforation intersecting portions, and both ends thereof open to the small diameter portion of the oil chamber. The oil chamber 15 is set such that the volumes of the oil chambers 15 a to 15 e are equal, and the sum of the volumes of the oil chambers 15 a to 15 e is at least twice the sum of the volumes of the supply oil passages 14.

  Journal distribution oil passages 17a, 17b, 17c, 17d, and 17e for supplying engine oil stored in the oil chamber 15 to a gap between the crank journal 12 and the bearing metal 8 are formed in the wall surfaces of the oil chambers 15a to 15e, respectively. Has been. The journal distribution oil passage 17 is bored in a direction passing through the axis A of the crank journal 12 and perpendicular to the supply oil passage 14, and is open on both sides of the outer peripheral surface of the crank journal 12. In addition, the journal distribution oil passage 17 is formed at a position where one or two rows per chamber avoid the frictional joint.

  On the other hand, pin distribution oil passages 18 a and 18 b that supply engine oil flowing in the supply oil passage 14 to the gap between the crank pin 11 and the bearing metal 9 are formed at the intersections of the linear drilling holes in each crankpin 11. , 18c, and 18d are formed. The pin distribution oil passage 18 is formed in a direction that passes through the axis of the crank pin 11 and is orthogonal to the supply oil passage 14, and opens on both sides of the outer peripheral surface of the crank pin 11. That is, the supply oil passage 14 and the pin distribution oil passage 18 form a T shape.

  The engine oil discharged by the oil pump 33 passes from the supply oil passage 14 through the journal distribution oil passage 17 or the pin distribution oil passage 18 to each sliding portion of the crankshaft 10, that is, the crank journal 12 and the bearing metal 8. , Or each gap between the crankpin 11 and the bearing metal 9.

<< Effects of Embodiment >>
Hereinafter, the operation of the present embodiment will be described with reference to FIG. FIG. 3 is an explanatory view showing the flow of engine oil flowing from the third crankpin 11c to the fourth crankpin 11d, and is a view of the crankshaft 10 viewed along the axial direction. The crankshaft 10 according to the present embodiment rotates about the axis A, and the centrifugal force F always acts on the engine oil flowing through the supply oil passage 14. At the intersection (the bent portion of the supply oil passage 14) in the third crankpin 11c, part of the engine oil flows into the pin distribution oil passage 18c formed in a direction orthogonal to the supply oil passage 14 by centrifugal force. To do. The remaining engine oil flows in the direction of the axis A against the centrifugal force F in the supply oil passage 14 from the third crankpin 11c to the fourth crank journal 12d. By flowing along the wall surface of the oil chamber 15, the oil flows to the supply oil passage 14 on the opposite side without resisting the centrifugal force F.

  In the fourth crank journal 12d, part of the engine oil flowing in the oil chamber 15 flows into the journal distribution oil passage 17d by the centrifugal force F of the crankshaft 10 and the discharge pressure of the oil pump 33. In the supply oil passage 14 from the fourth crank journal 12d to the fourth crankpin 11d, the remaining engine oil flows away from the axis A due to the centrifugal force F and the discharge pressure of the oil pump 33. In the bent portion of the supply oil passage 14 in the fourth crankpin 11d, a part of engine oil further flows into a pin distribution oil passage 18d formed in a direction orthogonal to the supply oil passage 14 by centrifugal force.

  FIG. 6 is an explanatory view showing the flow of engine oil in the solid crankshaft 50 according to the prior art. As shown in the figure, the centrifugal force F is constantly acting on the engine oil flowing through the supply oil passage 54 by the rotation of the solid crankshaft 50 according to the conventional technique around the axis A ′. In the supply oil passage 54 extending from the bent portion of the supply oil passage 54 in the third crank pin 51c to the center of the fourth crank journal 52d, centrifugal force F, which is the opposite component to the flow direction, acts on the engine oil. In the supply oil passage 54 extending from the center of the fourth crank journal 52d to the bent portion of the supply oil passage 54 in the fourth crank pin 51d, the same component centrifugal force F as that in the flow direction acts. Therefore, this is a factor that causes an even greater increase in pipe resistance in engine oil.

  In any crankshaft, the centrifugal force of the crankshaft 10 or the pressure drop of the engine oil discharged from the pin distribution oil passage affects other oil discharges, and the connecting acting on the crankpin 11. Due to deformation of the crankshaft 10 due to the load of the rod, pulsation is generated in the engine oil flowing through the supply oil passage 14. However, in the crankshaft 10 of this embodiment, since the oil chamber 15 is provided so as to divide the supply oil passage 14 at a substantially equal distance, pulsation is reduced in each oil chamber 15. Further, when viscous engine oil flows through the elongated supply oil passage, the oil pressure is lost, but the oil chamber 15 is formed, so that the oil pressure loss is reduced. Therefore, engine oil can be supplied to each crank journal 12 and crank pin 11 at a stable pressure.

  When the engine oil flows from the supply oil passage 14 into the oil chamber 15, the oil chamber has the small diameter portion 19 and the supply oil passage 14 opens to the small diameter portion 19 as described above. The decrease in hydraulic pressure is suppressed by gradually increasing the cross-sectional area. Further, even when engine oil flows from the oil chamber 15 into the supply oil passage 14, the small-diameter portion 19 gradually reduces the cross-sectional area of the oil passage, thereby suppressing a decrease in hydraulic pressure due to contraction. Thereby, engine oil can distribute | circulate favorably to each sliding part.

  As described above, the sum of the volumes of the oil chambers 15a to 15e is twice the sum of the volumes of the supply oil passages 14. However, as the magnification with respect to the sum of the volumes of the supply oil passages 14 increases, the pulsation reduction effect increases. Get higher. However, according to the present inventors, the effect is drastically reduced when the distance from the oil chamber 15 to the pin distribution oil passage 18 is large when the sum of the volumes of the supply oil passages 14 is less than twice. It has been confirmed.

  FIG. 4 is a graph showing changes in engine oil pressure in the crankshaft, where the vertical axis represents oil pressure (kPa) and the horizontal axis represents time (t). In addition, the solid line in a graph shows the oil pressure P of the crankshaft 10 which concerns on this embodiment, and the broken line has shown the oil pressure P 'in the solid crankshaft 50 by the prior art shown to FIG. 5 and FIG. .

  As shown in the figure, both crankshafts 10 and 50 pulsate in oil pressure with rotation, but the differential pressure D between the maximum value and the minimum value of the oil pressure P of the crankshaft 10 according to this embodiment is as follows. The pressure difference D ′ of the oil pressure P ′ of the solid crankshaft 50 is significantly smaller. In the solid crankshaft 50 according to the prior art, the oil pressure P ′ may be less than 0 and become negative, but in the crankshaft 10 according to the present embodiment, the oil pressure P does not become negative. . Further, the average value of the oil pressure P of the crankshaft 10 according to the present embodiment is larger than the average value of the oil pressure P ′ of the solid crankshaft 50 due to the effect of suppressing the pressure drop. These also ensure good engine oil distribution.

  Further, in the crankshaft 10 of the present embodiment, since no oil chamber is formed inside the crankpin 11, air accumulated in the oil chamber in the crankpin may flow out at a time and interrupt the engine oil. In addition, it is not necessary to take measures such as increasing the diameter of the crankpin in order to prevent a decrease in the rigidity of the crankpin. On the other hand, compared to the solid crankshaft 50, the crankshaft 10 achieves weight reduction of the crankshaft 10 by the oil chamber 15.

  Although the description of the specific embodiment is finished as above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the crankshaft of the present invention is applied to an in-line four-cylinder gasoline engine, but other types of engines such as a V-type and a horizontally opposed type, a gasoline engine, and the like may be employed. The number is not limited to this. In the above embodiment, the oil chamber is formed in all the five crank journals. However, if at least one oil chamber is formed, the above-described effect can be exhibited. In addition, various forms such as a form in which a plurality are formed only on the upstream side of the supply oil passage can be adopted. Furthermore, in the above embodiment, the oil chamber is formed by friction-joining the slow piece. However, if sufficient joining strength and joining accuracy can be obtained, the slow piece can be obtained by other methods such as arc welding or adhesion. May be joined. In addition to these changes, the form of the oil chamber and the form of the oil passage can be appropriately changed without departing from the spirit of the present invention.

Sectional drawing of the principal part of the engine provided with the crankshaft which concerns on embodiment The expanded sectional view of the crankshaft concerning an embodiment Explanatory drawing which shows the flow of the engine oil in the crankshaft which concerns on embodiment The graph which shows the pressure change of the engine oil in the crankshaft which concerns on embodiment Cross-sectional view of a crankshaft according to the prior art Explanatory drawing showing the flow of engine oil in the crankshaft according to the prior art

Explanation of symbols

E Engine 10 Crankshaft 10a One end portion 11 Crank pin 12 Crank journal 13 Crank arm 14 Supply oil passage 15 Oil chamber 17 Journal distribution oil passage 18 Pin distribution oil passage 19 Small diameter portion 20 Large diameter portion 21 First throw piece 22 Second throw Piece 23 Third throw piece 24 Fourth throw piece 25 Extension piece 26 Extension piece

Claims (4)

An oil introduction hole for introducing engine oil is formed in the vicinity of one end thereof, and the engine oil introduced from the oil introduction hole is supplied to a distribution oil passage formed in each crank journal and each crank pin. A center oil supply type crankshaft having a supply oil passage,
A center oil supply type crankshaft characterized in that at least one oil chamber for storing engine oil flowing through the supply oil passage is formed only in the crank journal.   The center oil supply type crankshaft according to claim 1, wherein the oil chamber has a substantially cylindrical shape having a crankshaft as its center. The oil chamber has small diameter portions at both ends thereof,
The center oil supply type crankshaft according to claim 2, wherein the supply oil passage opens to the small diameter portion.   The center oil supply type crankshaft according to any one of claims 1 to 3, wherein the sum of the volumes of the oil chambers is at least twice the sum of the volumes of the supply oil passages.

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